1. Field of the Invention
The present invention relates to an image processing apparatus that automatically detects an object in an image and adaptively assigns an encoding amount in accordance with the relative degree of importance of the detected region.
2. Description of the Related Art
Conventionally, image encoding has been used to compress the data size of images, and the JPEG system standardized by the ISO (Internal Organization for Standardization) is widely used as an encoding system for still images. Also, the MPEG system, the H.264 system and the like, which have also been standardized by the ISO, are widely used as encoding systems for video.
It has been a fact that when lossy compression is used in such encoding systems, image quality degrades due to the amount of information being increasingly reduced the higher the frequency component of a region is. Japanese Patent Laid-Open No. 2000-197050 discloses technology for reducing such image degradation as much as possible in an important region (e.g., a person's face or body) in a captured image. In other words, a proposal has been made for the use of an image processing method called “recognition processing” for automatically detecting a specified object pattern in an image. One example of such technology for detecting a face in an image is the detection system by pattern matching with use of templates disclosed by Yang, et al. in “Detecting Faces in Images: A Survey” (see IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 24, No. 1, January 2002).
However, the system disclosed in Japanese Patent Laid-Open No. 2000-197050 simply detects faces in an image and assigns a high encoding amount to the detected regions. The encoded data size therefore increases significantly. In view of usage such as monitoring with use of a network camera, which has been on a rising trend in recent years, there has been an increasing need to take communication load into consideration. In other words, there is demand for the ability to suppress the encoded data size of image data as much as possible in a lossy compression process for image data.